De novo Inflammatory Bowel Disease in Kidney Transplant Recipients: A Single-Center Case Series Study.

Introduction: Gastrointestinal complications are common after solid organ transplantation. New-onset inflammatory bowel disease (IBD) after transplantation (de novo) is a major differential diagnosis of diarrhea after liver transplantation (LT) because of its high incidence in the field. However, the incidence of IBD after kidney transplantation (KT) remains unknown. Methods: This case series comprised six de novo IBD patients who had undergone KT at our hospital from April 1998 to December 2020. In this period, 232 KT recipients were identified. Participants were analyzed based on their colonoscopy diagnoses. Detailed clinical information regarding both KT- and IBD-related symptoms or outcomes was obtained, and we calculated the incidence of de novo IBD from the date of KT. Results: Of the 232 recipients in the median observation period of 6.1 (interquartile range: 2.6, 10.8) years, six recipients (one with Crohn's disease and five with ulcerative colitis) were diagnosed with de novo IBD. The incidence of de novo IBD after KT was 355.8/100,000 person-years (95% confidence interval, 159.8-791.9 per 100,000 person-years). Bloody stools and diarrhea did not always occur, with bloody stools occurring in three and diarrhea in 2 patients at the time of diagnosis. No recipient developed graft failure or extraintestinal complications (e.g., IBD-related nephritis or arthritis). Conclusion: Despite a small sample size, this study's results indicate that the incidence of de novo IBD after KT may be similar to that after LT and higher than that in the general population. Larger studies are required to validate these preliminary findings.